Investigation On Resistance Characteristics Of Single-Phase And Two-Phase Flow In Narrow Tube-Bundle Channel

Steam-Liquid two-phase flow and heat transfer is widely presented in exchange equipments of dynamical, nuclear energy, chemistry, petroleum and other industries. Especially the reactor thermal hydraulic analysis, flow and heat transfer in steam generators, steam turbines and steam condensers, are all typical problems of two-phase flow.The research of flow and heat transfer characters in narrow tube-bundle channel has an important meaning in improving the safety and economy of steam generators and nuclear reactors; it is very helpful to promote the nationalization level of nuclear power technology, and can ensure the safe and effective utilization of nuclear energy. The thesis attempts to investigate the flow and heat transfer characters in this special channel, thus provides a reference basis for engineering application.By means of mass documents research, the author and studying team set up the experimental bench of flow and heat transfer in vertical tube-bundle channel. Two channels with different equivalent diameter have been tested. Experimental research and theoretical analysis on single-phase and two-phase flow characteristic are presented; the main content of research is as follows:(1) The single-phase flow resistance characteristic in narrow tube bundle channel is different with ordinary circle or annular channels. These differences have connections with special geometrical structure and variation of viscosity and density caused by heat flux. According to the experimental data, the empirical correlation of frictional resistance coefficient is obtained.(2) There is a close relationship between flow resistance and heat exchange in narrow tube-bundle channel. According to modified Reynolds analogy, forced convection heat transfer in turbulent flow region is predicted, using frictional resistance coefficient which has been obtained.(3) The flow boiling experiment in vertical narrow tube-bundle channel has been accomplished. The total boiling pressure drop and frictional pressure drop are analyzed deeply, according to the experimental data. The boiling pressure drop increases with the increase of heat flux and mass flux. The effect of heat flux on two-phase pressure drop is mainly realized by the change of dryness fraction.(4) The influences of different factors on boiling frictional pressure and two-phase frictional multiplier are studied. Combined with the traditional correlation and considered the speciality of the narrow tube-bundle channel, a new empirical correlation has been obtained by modifying the formulas of Chisholm B and Tran.